Cleanroom Standards

There are two standards that our users typically refer to; the old FS209E standard which contained six classes, and the international replacement ISO 14644-1 classification system which adds two cleaner standards and one dirtier standard

FS209E cleanroom classifications were rated according to how much particulate of specific sizes exist per cubic foot (see chart below). The “cleanest” cleanroom in FS209E is referred to as Class 1; the “dirtiest” cleanroom is a class 100,000.

ISO 14644-1 cleanroom classifications are rated according to how much particulate of specific sizes exist per cubic meter (see the second chart). The “cleanest” cleanroom is a class 1 and the “dirtiest” a class 9. ISO class 3 is approximately equal to FS209E class 1, while ISO class 8 approximately equals FS209E class 100,000.

Airborne Particulate Cleanliness Class Comparison

ISO 14644-1Federal Standard 209EEU GMP Annex 1
ISO ClassEnglishMetric
ISO 1
ISO 2
ISO 31M1.5
ISO 410M2.5
ISO 4.5Grade A
ISO 5100M3.5
ISO 61,000M4.5
ISO 710,000M5.5Grade B
ISO 8100,000M6.5Grade C+D
ISO 9

Airborne Particulate Cleanliness Classes (By Cubic Meter):

ClassNumber of Particles per Cubic Meter by Micrometer Size
0.1μm0.2μm0.3μm0.5μm1μm5μm
ISO1102
ISO21002410
ISO31,00023710235
ISO410,0002,3701,02035283
ISO5100,00023,70010,2003,520832
ISO61,000,000237,000102,00035,2008,320293
ISO7352,00083,2002,930
ISO83,520,000832,00029,300
ISO935,200,0008,320,000293,000

Airborne Particulate Cleanliness Classes (By Cubic Meter):

ClassNumber of Particles per Cubic Meter by Micrometer Size
0.1μm0.2μm0.3μm0.5μm1μm5μm
ISO1102
ISO21002410
ISO31,00023710235
ISO410,0002,3701,02035283
ISO5100,00023,70010,2003,520832
ISO61,000,000237,000102,00035,2008,320293
ISO7352,00083,2002,930
ISO83,520,000832,00029,300
ISO935,200,0008,320,000293,000

In cleanrooms, particulate concentration changes over time — from the construction and installation of equipment to its operational status. ISO delineates three cleanroom classification standards: as-built, at-rest and operational. As instruments and equipment are introduced and particulates rise, an “as-built” cleanroom becomes an “at-rest” cleanroom. When people are added to the matrix, particulate levels rise still further in the “operational” cleanroom.

ISO 14644-2 describes the type and frequency of testing required to conform to certain standards. The following tables indicate mandatory and optional tests.

Required Testing (ISO 14644-2)

Schedule of Tests to Demonstrate Continuing Compliance

Test ParameterClassMaximum Time IntervalTest Procedure
Particle Count Test≤ ISO 46 MonthsISO 14644-1 Annex A
> ISO 512 Months
Air Pressure DifferenceAll Classes12 MonthsISO 14644-1 Annex B5
AirflowAll Classes12 MonthsISO 14644-1 Annex B4

Optional Testing (ISO 14644-2)

Schedule of Additional Optional Tests

Test ParameterClassMaximum Time IntervalTest Procedure
Installed Filter LeakageAll Classes24 MonthsISO 14644-1 Annex B6
Containment LeakageAll Classes24 MonthsISO 14644-1 Annex B4
RecoveryAll Classes24 MonthsISO 14644-1 Annex B13
Airflow VisualizationAll Classes24 MonthsISO 14644-1 Annex B7